In packs using traditional horizontal supports, the bag is hung on the support and has a tendency to swing or rock with the motion of the bicycle. This unwanted motion is most noticeable on quick stops and can be a serious hazard, especially when the packs are full and heavy. In addition, the bags tend to bulge beyond their normal geometrical shape when full and may encroach on other equipment, the bicycle parts or the rider's freedom. This is especially so when the pack is handlebar mounted and may intefere with the rider's access to the hand brakes or the maneuverability of the handlebars.